Back in the olden days, crank arms were designed to be at a right angle to the bottom bracket spindle. That required a bottom bracket spindle in the 120's to space the chainring out far enough to miss the frame's chain stay.

Modern square taper cranksets have the crank arms angled or offset outward a skosh. Some are offset a little more than others. The good news is that they allow much shorter bottom bracket spindles to be used. The bad news is that now you have to match the bottom bracket with the crankset.